Anti-flagellin antibody responses elicited in mice orally immunized with attenuated Salmonella enterica serovar Typhimurium vaccine strains

In the present study we investigated the flagellin-specific serum (IgG) and fecal (IgA) antibody responses elicited in BALB/c mice immunized with isogenic mutant derivatives of the attenuated Salmonella enterica serovar Typhimurium (S. Typhimurium) SL3261 strain expressing phase 1 (FliCi), phase 2 (FljB), or no endogenous flagellin. The data reported here indicate that mice orally immunized with recombinant S. Typhimurium strains do not mount significant systemic or secreted antibody responses to FliCi, FljB or heterologous B-cell epitopes genetically fused to FliCi. These findings are particularly relevant for those interested in the use of flagellins as molecular carriers of heterologous antigens vectored by attenuated S. Typhimurium strains.

Novo dispositivo para aferição de KVp e dose em equipamentos de radiodiagnóstico / New device for kVp and dose measurements of diagnostic X-ray tubes

Neste artigo é apresentado um novo dispositivo para aferição do pontecial aplicado entre os eletrodos de um tubo radiográfico. Ele opera utilizando um sensor de raios-X à base de silício e o sistema eletrônico empregado deriva de um instrumento detector de cintilação desenvolvido anteriormente. No trabalho são apresentados, também, os resultados da calibração e dos testes realizados com um equipamento convencional de radiodiagnóstico, com um mamógrafo e com um aparelho de raios-X odontológico. Além disso, uma ampliação do circuito eletrônico tambem permite que o dispositivo possa atuar como dosímetro. São discutidas as vantagens desse novo dispositivo numa comparação com outros instrumentos de aferição de kVp, incluindo o detector de cintilaçao proposto anteriormente.

Ligand-specific opening of a gated-porin channel in the outer membrane of living bacteria.

Ligand-gated membrane channels selectively facilitate the entry of iron into prokaryotic cells. The essential role of iron in metabolism makes its acquisition a determinant of bacterial pathogenesis and a target for therapeutic strategies. In Gram-negative bacteria, TonB-dependent outer membrane proteins form energized, gated pores that bind iron chelates (siderophores) and internalize them. The time-resolved operation of the Escherichia coli ferric enterobactin receptor FepA was observed in vivo with electron spin resonance spectroscopy by monitoring the mobility of covalently bound nitroxide spin labels. A ligand-binding surface loop of FepA, which normally closes its transmembrane channel, exhibited energy-dependent structural changes during iron and toxin (colicin) transport. These changes were not merely associated with ligand binding, but occurred during ligand uptake through the outer membrane bilayer. The results demonstrate by a physical method that gated-porin channels open and close during membrane transport in vivo.